SENIOR SNP figures believe left-wing activists close to perjurer Tommy Sheridan have infiltrated the party’s branches in North Lanarkshire.

Three insiders, speaking on condition of anonymity, believe the so-called entryists are trying persuade new SNP members to give Sheridan’s Solidarity party their second vote at next year’s Holyrood election.

Despite being on the losing side in last year’s referendum, the SNP membership surged to over 100,000 within a few months.

However, some Nationalists believe many of the new members represent the brand of leftism associated with Sheridan, a former Glasgow MSP.

The three sources – who are in Uddingston & Bellshill, Airdrie & Shotts, and Coatbridge & Chryston constituency branches – told this newspaper about their fears of infiltration by Solidarity supporters.

They said party members sympathetic to Sheridan have disrupted branch meetings and tried to influence selection contests.

Sheridan was jailed for perjury in 2011 after he was found guilty of telling lies about his attendance at a sex club in Manchester.

Despite his conviction, the Solidarity leader is eyeing a Holyrood comeback and announced recently he would be a candidate next year.

However, the SNP is expected to win all first-past-the-post seats in the 2016 poll but potentially none on the regional Lists.

This has prompted Sheridan to make an explicit pitch to independence supporters about backing his party on the List system.

One source said of the alleged entryism: “It’s clear as day that people close to Tommy are trying to take over the branches, positioning themselves for Tommy.”

“It’s like a virus and it’s spreading. Party headquarters better get off its backside.

“The plan seems to be to agitate and get local members to give Solidarity their second vote.”

The second North Lanarkshire insider said: “The local party has been infiltrated by folk close to Tommy. They are going around saying ‘vote Solidarity on the List’. They have no loyalty to the SNP and are pushing a different agenda.”

The third source added: “There is definitely infiltration here by extreme left elements that are positive towards Solidarity. Giving Solidarity the second vote next year seems to be the strategy.”

Solidarity recently changed its rules to allow any member to hold dual membership with another party, a rethink that was interpreted as encouraging key figures to join the SNP.

Sheridan also called for an SNP vote at May’s general election, a strategy that split his party.

One of his key allies, John Park, is based in South Lanarkshire, while a councillor in the same local authority area recently defected from the Nationalists to Solidarity.

Park is also an influential figure in the Hope Over Fear campaign, which is widely viewed in pro-independence circles as a Sheridan front group.

According to minutes of an Uddingston and Bellshill SNP meeting in May, party headquarters were alerted to concerns about a local SNP fundraising operation at a Hope Over Fear rally in Glasgow’s George Square.

An SNP spokesperson said: "At next year's Scottish election we hope that as many people as possible across Scotland will continue to put their trust in the SNP on both the regional and the constituency vote - and SNP members across the country will be working hard to encourage people to give both votes to the SNP.”